U.S. patent application number 13/041905 was filed with the patent office on 2012-09-13 for tunable antenna system with receiver diversity.
Invention is credited to Ruben Caballero, Nanbo Jin, Matt A. Mow, Mattia Pascolini, Robert W. Schlub.
Application Number | 20120229347 13/041905 |
Document ID | / |
Family ID | 45774096 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120229347 |
Kind Code |
A1 |
Jin; Nanbo ; et al. |
September 13, 2012 |
TUNABLE ANTENNA SYSTEM WITH RECEIVER DIVERSITY
Abstract
A wireless electronic device may include antenna structures and
antenna tuning circuitry. The device may include a display mounted
within a housing. A peripheral conductive member may run around the
edges of the display and housing. Dielectric-filled gaps may divide
the peripheral conductive member into individual segments. A ground
plane may be formed within the housing. The ground plane and the
segments of the peripheral conductive member may form antennas in
upper and lower portions of the housing. The antenna tuning
circuitry may include switchable inductor circuits and variable
capacitor circuits for the upper and lower antennas. The switchable
inductor circuits associated with the upper antenna may be tuned to
provide coverage in at least two high-band frequency ranges of
interest, whereas the variable capacitor circuits associated with
the upper antenna may be tuned to provide coverage in at least two
low-band frequency ranges of interest.
Inventors: |
Jin; Nanbo; (Sunnyvale,
CA) ; Pascolini; Mattia; (San Mateo, CA) ;
Mow; Matt A.; (Los Altos, CA) ; Schlub; Robert
W.; (Cupertino, CA) ; Caballero; Ruben; (San
Jose, CA) |
Family ID: |
45774096 |
Appl. No.: |
13/041905 |
Filed: |
March 7, 2011 |
Current U.S.
Class: |
343/702 |
Current CPC
Class: |
H01Q 1/44 20130101; H01Q
9/42 20130101; H01L 2924/19107 20130101; H01Q 1/243 20130101; H01Q
5/307 20150115; H01Q 21/28 20130101; H01Q 9/14 20130101; H01Q 7/00
20130101 |
Class at
Publication: |
343/702 |
International
Class: |
H01Q 1/24 20060101
H01Q001/24; H01Q 5/01 20060101 H01Q005/01 |
Claims
1. An electronic device comprising: a housing having a peripheral
conductive member that runs around at least some edges of the
housing; an inverted-F antenna that is formed from an antenna
ground and a portion of the peripheral conductive member; and a
switchable inductor coupled between the antenna ground and the
portion of the peripheral conductive member.
2. The electronic device defined in claim 1, wherein the peripheral
conductive member comprises at least one gap that divides the
peripheral conductive member into a plurality of segments and
wherein the portion includes at least one of the plurality of
segments.
3. The electronic device defined in claim 2, wherein the antenna
ground includes conductive housing structures formed within the
electronic device.
4. The electronic device defined in claim 3, wherein the conductive
housing structures comprises a printed circuit board.
5. The electronic device defined in claim 2, wherein the inverted-F
antenna comprises first and second antenna feed terminals and
wherein the switchable inductor is coupled between the first and
second antenna feed terminals.
6. The electronic device defined in claim 5, wherein the switchable
inductor comprises an inductor and a switch that are connected in
series between the first and second antenna feed terminals.
7. The electronic device defined in claim 6, further comprising:
wireless transceiver circuitry, wherein the wireless transceiver
circuitry is coupled to the first antenna feed terminal.
8. The electronic device defined in claim 7, further comprising: a
conductive path coupled in parallel with the switchable inductor
between the first and second antenna feed terminals.
9. The electronic device defined in claim 8, further comprising: a
variable capacitor circuit that bridges the at least one gap in the
peripheral conductive member.
10. A wireless electronic device comprising: a housing containing
conductive structures that form an antenna ground and having a
peripheral conductive member that runs around at least some edges
of the housing; an antenna that is formed from the antenna ground
and a portion of the peripheral conductive member; and a switchable
inductor circuit coupled between the antenna ground and the portion
of the peripheral conductive member, wherein: when the switchable
inductor circuit is switched out of use, the antenna is configured
to operate in a low-band frequency range and in a first high-band
frequency range; and when the switchable inductor circuit is
switched into use, the antenna is configured to operate in the
low-band frequency range and is configured to operate in a second
high-band frequency range that is higher in frequency than the
first high-band frequency range.
11. The wireless electronic device defined in claim 10, wherein the
antenna comprises first and second antenna feed terminals and
wherein the switchable inductor circuit is coupled between the
first and second antenna feed terminals, further comprising:
wireless transceiver circuitry coupled to the first antenna feed
terminal.
12. The wireless electronic device defined in claim 11, wherein the
antenna comprises an inverted-F antenna.
13. The wireless electronic device defined in claim 12, wherein the
peripheral conductive member has at least two gaps, further
comprising: a variable capacitor circuit that bridges one of the
two gaps.
14. The wireless electronic device defined in claim 12, wherein the
switchable inductor circuit comprises an inductor and a switch that
are connected in series between the first and second antenna feed
terminals.
15. The wireless electronic device defined in claim 12, wherein the
switchable inductor circuit comprises: a switch; a first inductor,
wherein the first inductor and the switch are coupled in series
between the first and second antenna feed terminals; and a second
inductor, wherein the second inductor and the switch are coupled in
series between the first and second antenna feed terminals.
16. The wireless electronic device defined in claim 12, wherein the
switchable inductor circuit comprises: first and second switches; a
first inductor, wherein the first inductor and the first switch are
coupled in series between the first and second antenna feed
terminals; and a second inductor, wherein the second inductor and
the second switch are coupled in series between the first and
second antenna feed terminals.
17. A wireless electronic device comprising: a housing having a
periphery; a conductive structure that runs along the periphery and
that has at least two gaps on the periphery; and an inverted-F
antenna formed at least partly from the conductive structure; and a
variable capacitor that bridges at least one of the two gaps in the
peripheral conductive member, wherein: when the variable capacitor
is tuned to provide a first capacitance, the inverted-F antenna is
configured to operate in a first low-band frequency range and in a
high-band frequency range; and when the variable capacitor is tuned
to provide a second capacitance that is different than the first
capacitance, the inverted-F antenna is configured to operate in a
second low-band frequency range that is lower in frequency than the
first low-band frequency range and is configured to operate in the
high-band frequency range.
18. The wireless electronic device defined in claim 17, wherein the
inverted-F antenna comprises first and second antenna feed
terminals, further comprising: wireless transceiver circuitry
coupled to the first antenna feed terminal.
19. The wireless electronic device defined in claim 18, further
comprising: a switchable inductor coupled between the first and
second antenna feed terminals.
20. The wireless electronic device defined in claim 19, wherein the
switchable inductor comprises an inductor and a switch that are
coupled in series between the first and second antenna feed
terminals.
21. The wireless electronic device defined in claim 20, further
comprising a conductive shorting path coupled in parallel with the
switchable inductor between the first and second antenna feed
terminals.
22. The wireless electronic device defined in claim 17, further
comprising: processing circuitry, wherein the processing circuitry
generates control signals that tunes the variable capacitor to
provide the first and second capacitance.
Description
BACKGROUND
[0001] This relates generally to wireless communications circuitry,
and more particularly, to electronic devices that have wireless
communications circuitry.
[0002] Electronic devices such as portable computers and cellular
telephones are often provided with wireless communications
capabilities. For example, electronic devices may use long-range
wireless communications circuitry such as cellular telephone
circuitry to communicate using cellular telephone bands at 850 MHz,
900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz. Electronic devices may
use short-range wireless communications links to handle
communications with nearby equipment. For example, electronic
devices may communicate using the WiFi.RTM. (IEEE 802.11) bands at
2.4 GHz and 5 GHz and the Bluetooth.RTM. band at 2.4 GHz.
[0003] To satisfy consumer demand for small form factor wireless
devices, manufacturers are continually striving to implement
wireless communications circuitry such as antenna components using
compact structures. However, it can be difficult to fit
conventional antenna structures into small devices. For example,
antennas that are confined to small volumes often exhibit narrower
operating bandwidths than antennas that are implemented in larger
volumes. If the bandwidth of an antenna becomes too small, the
antenna will not be able to cover all communications bands of
interest.
[0004] In view of these considerations, it would be desirable to
provide improved wireless circuitry for electronic devices.
SUMMARY
[0005] Electronic devices may be provided that contain wireless
communications circuitry. The wireless communications circuitry may
include radio-frequency transceiver circuitry and antenna
structures. An electronic device may include a display mounted
within a housing. A peripheral conductive member may run around the
edges of the display and housing.
[0006] The peripheral conductive member may be divided into
individual segments by forming gaps in the peripheral conductive
member at various points along its length. The gaps may be filled
with a dielectric such as plastic and may form an open circuit
between opposing portions of the conductive member. With one
illustrative configuration, three gaps may be formed in the
peripheral conductive member to divide the peripheral conductive
member into three respective segments.
[0007] A conductive housing member such as a conductive midplate
member that spans the width of the housing may be connected to the
peripheral conductive member at the left and right edges of the
display. The conductive housing member and other conductive
structures such as electrical components and printed circuits may
form a ground plane. The ground plane and the peripheral conductive
member segments may surround dielectric openings to form the
antenna structures. For example, an upper cellular telephone
antenna may be formed at an upper end of the housing and a lower
cellular telephone antenna may be formed at a lower end of the
housing. In the upper cellular telephone antenna, a first
dielectric opening may be surrounded by at least some of a first
peripheral conductive member segment and portions of the ground
plane. In the lower cellular telephone antenna, a second dielectric
opening may be surrounded by at least some of a second peripheral
conductive member segment and portions of the ground plane. The
upper cellular telephone antenna may be a two-branch inverted-F
antenna. The lower cellular telephone antenna may be a loop
antenna.
[0008] The upper and lower antennas may include associated antenna
tuning circuitry. The antenna tuning circuitry may include
switchable inductor circuits that bridge the first and second
peripheral conductive member segments to the ground plate, tunable
impedance matching circuitry, and variable capacitor circuitry
bridging each of the gaps in the peripheral conductive member. The
tunable matching circuitry may be used to couple the
radio-frequency transceiver circuitry to the lower and upper
antennas.
[0009] During operation of the electronic device, the lower antenna
may serve as the primary cellular antenna for the device.
Radio-frequency antenna signals may be transmitted and received by
the lower antenna in cellular telephone bands such as the bands at
750 MHz, 850 MHz, 900
[0010] MHz, 1800 MHz, 1900 MHz, and 2100 MHz. The upper antenna may
serve as a secondary antenna that allows the electronic device to
implement receiver diversity. When the performance of the lower
antenna drops during operation, the radio-frequency transceiver
circuitry in the device can receive signals with the upper antenna
rather than the lower antenna.
[0011] The upper antenna may support only a subset of the bands
that are supported by the lower antenna. During a first antenna
mode in which the switchable inductor associated with the upper
antenna is turned off and the variable capacitors associated with
the upper antenna is tuned to exhibit a low capacitance value, the
upper antenna may support a first low-band frequency range (e.g., a
low-band region that covers 850 MHz and 900 MHz) and a first
high-band frequency range (e.g., a high-band region that covers
1800 MHz and 1900 MHz). The coverage of the upper antenna can be
extended by tuning the antenna tuning circuitry associated with the
upper antenna in real time.
[0012] For example, the upper antenna may be configured in a second
antenna mode in which the variable capacitors are tuned to exhibit
higher capacitance values so that the upper antenna may support a
second low-band frequency range (e.g., a low-band region that
covers 750 MHz) that is lower in frequency than the first low-band
frequency range. The upper antenna may be configured in a third
antenna mode in which the switchable inductor is turned on so that
the upper antenna may support a second high-band frequency range
(e.g., a high-band region that covers 2100 MHz) that is higher in
frequency than the first high-band frequency range.
[0013] Further features of the invention, its nature and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of an illustrative electronic
device with wireless communications circuitry in accordance with an
embodiment of the present invention.
[0015] FIG. 2 is a schematic diagram of an illustrative electronic
device with wireless communications circuitry in accordance with an
embodiment of the present invention.
[0016] FIG. 3 is a cross-sectional end view of an illustrative
electronic device with wireless communications circuitry in
accordance with an embodiment of the present invention.
[0017] FIG. 4 is a diagram of illustrative wireless circuitry
including multiple antennas in accordance with an embodiment of the
present invention.
[0018] FIGS. 5A and 5B are circuit diagrams showing illustrative
tunable impedance matching circuitry of the type that may be used
in connection with the wireless circuitry of FIG. 4 in accordance
with an embodiment of the present invention.
[0019] FIG. 6 is a diagram of an electronic device of the type
shown in FIG. 1 showing how antennas with antenna tuning circuitry
may be formed within the device in accordance with an embodiment of
the present invention.
[0020] FIGS. 7-9 are diagrams of an antenna of the type shown in
the upper portion of the device of FIG. 6 in accordance with an
embodiment of the present invention.
[0021] FIG. 10 is a chart showing how antennas of the type shown in
FIG. 6 may be used in covering communications bands of interest by
adjusting associated antenna tuning circuitry in accordance with an
embodiment of the present invention.
[0022] FIG. 11 is a plot showing how the upper antenna of FIG. 6
may be tuned to cover multiple low-band frequency ranges of
interest in accordance with an embodiment of the present
invention.
[0023] FIG. 12 is a plot showing how the upper antenna of FIG. 6
may be tuned to cover multiple high-band frequency ranges of
interest in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION
[0024] Electronic devices may be provided with wireless
communications circuitry. The wireless communications circuitry may
be used to support wireless communications in multiple wireless
communications bands. The wireless communications circuitry may
include one or more antennas.
[0025] The antennas can include loop antennas, inverted-F antennas,
strip antennas, planar inverted-F antennas, slot antennas, hybrid
antennas that include antenna structures of more than one type, or
other suitable antennas. Conductive structures for the antennas
may, if desired, be formed from conductive electronic device
structures. The conductive electronic device structures may include
conductive housing structures. The housing structures may include a
peripheral conductive member that runs around the periphery of an
electronic device. The peripheral conductive member may serve as a
bezel for a planar structure such as a display, may serve as
sidewall structures for a device housing, or may form other housing
structures. Gaps in the peripheral conductive member may be
associated with the antennas.
[0026] An illustrative electronic device of the type that may be
provided with one or more antennas is shown in FIG. 1. Electronic
device 10 may be a portable electronic device or other suitable
electronic device. For example, electronic device 10 may be a
laptop computer, a tablet computer, a somewhat smaller device such
as a wrist-watch device, pendant device, headphone device, earpiece
device, or other wearable or miniature device, a cellular
telephone, a media player, etc.
[0027] Device 10 may include a housing such as housing 12. Housing
12, which may sometimes be referred to as a case, may be formed of
plastic, glass, ceramics, fiber composites, metal (e.g., stainless
steel, aluminum, etc.), other suitable materials, or a combination
of these materials. In some situations, parts of housing 12 may be
formed from dielectric or other low-conductivity material. In other
situations, housing 12 or at least some of the structures that make
up housing 12 may be formed from metal elements.
[0028] Device 10 may, if desired, have a display such as display
14. Display 14 may, for example, be a touch screen that
incorporates capacitive touch electrodes. Display 14 may include
image pixels formed from light-emitting diodes (LEDs), organic LEDs
(OLEDs), plasma cells, electronic ink elements, liquid crystal
display (LCD) components, or other suitable image pixel structures.
A cover glass layer may cover the surface of display 14. Buttons
such as button 19 may pass through openings in the cover glass.
[0029] Housing 12 may include structures such as peripheral member
16. Member 16 may run around the rectangular periphery of device 10
and display 14. Member 16 or part of member 16 may serve as a bezel
for display 14 (e.g., a cosmetic trim that surrounds all four sides
of display 14 and/or helps hold display 14 to device 10). Member 16
may also, if desired, form sidewall structures for device 10.
[0030] Member 16 may be formed of a conductive material and may
therefore sometimes be referred to as a peripheral conductive
member or conductive housing structures. Member 16 may be formed
from a metal such as stainless steel, aluminum, or other suitable
materials. One, two, or more than two separate structures may be
used in forming member 16. In a typical configuration, member 16
may have a thickness (dimension TT) of about 0.1 mm to 3 mm (as an
example). The sidewall portions of member 16 may, as an example, be
substantially vertical (parallel to vertical axis V). Parallel to
axis V, member 16 may have a dimension TZ of about 1 mm to 2 cm (as
an example). The aspect ratio R of member 16 (i.e., the ratio R of
TZ to TT) is typically more than 1 (i.e., R may be greater than or
equal to 1, greater than or equal to 2, greater than or equal to 4,
greater than or equal to 10, etc.).
[0031] It is not necessary for member 16 to have a uniform
cross-section. For example, the top portion of member 16 may, if
desired, have an inwardly protruding lip that helps hold display 14
in place. If desired, the bottom portion of member 16 may also have
an enlarged lip (e.g., in the plane of the rear surface of device
10). In the example of FIG. 1, member 16 has substantially straight
vertical sidewalls. This is merely illustrative. The sidewalls of
member 16 may be curved or may have any other suitable shape. In
some configurations (e.g., when member 16 serves as a bezel for
display 14), member 16 may run around the lip of housing 12 (i.e.,
member 16 may cover only the edge of housing 12 that surrounds
display 14 and not the rear edge of housing 12 of the sidewalls of
housing 12).
[0032] Display 14 may include conductive structures such as an
array of capacitive electrodes, conductive lines for addressing
pixel elements, driver circuits, etc. Housing 12 also include
internal structures such as metal frame members, a planar housing
member (sometimes referred to as a midplate) that spans the walls
of housing 12 (i.e., a substantially rectangular member that is
welded or otherwise connected between opposing sides of member 16),
printed circuit boards, and other internal conductive structures.
These conductive structures may be located in center CN of housing
12 (as an example).
[0033] In regions 22 and 20, openings may be formed between the
conductive housing structures and conductive electrical components
that make up device 10. These openings may be filled with air,
plastic, or other dielectrics. Conductive housing structures and
other conductive structures in region CN of device 10 may serve as
a ground plane for the antennas in device 10. The openings in
regions 20 and 22 may serve as slots in open or closed slot
antennas, may serve as a central dielectric region that is
surrounded by a conductive path of materials in a loop antenna, may
serve as a space that separates an antenna resonating element such
as a strip antenna resonating element or an inverted-F antenna
resonating element from the ground plane, or may otherwise serve as
part of antenna structures formed in regions 20 and 22.
[0034] Portions of member 16 may be provided with gap structures.
For example, member 16 may be provided with one or more gaps such
as gaps 18A, 18B, 18C, and 18D, as shown in FIG. 1. The gaps may be
filled with dielectric such as polymer, ceramic, glass, etc. Gaps
18A, 18B, 18C, and 18D may divide member 16 into one or more
peripheral conductive member segments. There may be, for example,
two segments of member 16 (e.g., in an arrangement with two gaps),
three segments of member 16 (e.g., in an arrangement with three
gaps), four segments of member 16 (e.g., in an arrangement with
four gaps, etc.). The segments of peripheral conductive member 16
that are formed in this way may form parts of antennas in device
10.
[0035] In a typical scenario, device 10 may have upper and lower
antennas (as an example). An upper antenna may, for example, be
formed at the upper end of device 10 in region 22. A lower antenna
may, for example, be formed at the lower end of device 10 in region
20. The antennas may be used separately to cover separate
communications bands of interest or may be used together to
implement an antenna diversity scheme or a
multiple-input-multiple-output (MIMO) antenna scheme.
[0036] Antennas in device 10 may be used to support any
communications bands of interest. For example, device 10 may
include antenna structures for supporting local area network
communications, voice and data cellular telephone communications,
global positioning system (GPS) communications or other satellite
navigation system communications, Bluetooth.RTM. communications,
etc.
[0037] A schematic diagram of electronic device 10 is shown in FIG.
2. As shown in FIG. 2, electronic device 10 may include storage and
processing circuitry 28. Storage and processing circuitry 28 may
include storage such as hard disk drive storage, nonvolatile memory
(e.g., flash memory or other electrically-programmable-read-only
memory configured to form a solid state drive), volatile memory
(e.g., static or dynamic random-access-memory), etc. Processing
circuitry in storage and processing circuitry 28 may be used to
control the operation of device 10. This processing circuitry may
be based on one or more microprocessors, microcontrollers, digital
signal processors, baseband processors, power management units,
audio codec chips, application specific integrated circuits,
etc.
[0038] Storage and processing circuitry 28 may be used to run
software on device 10, such as internet browsing applications,
voice-over-internet-protocol (VOIP) telephone call applications,
email applications, media playback applications, operating system
functions, etc. To support interactions with external equipment,
storage and processing circuitry 28 may be used in implementing
communications protocols. Communications protocols that may be
implemented using storage and processing circuitry 28 include
internet protocols, wireless local area network protocols (e.g.,
IEEE 802.11 protocols--sometimes referred to as WiFi.RTM.),
protocols for other short-range wireless communications links such
as the Bluetooth.RTM. protocol, cellular telephone protocols,
etc.
[0039] Circuitry 28 may be configured to implement control
algorithms that control the use of antennas in device 10. For
example, to support antenna diversity schemes and MIMO schemes or
other multi-antenna schemes, circuitry 28 may perform signal
quality monitoring operations, sensor monitoring operations, and
other data gathering operations and may, in response to the
gathered data, control which antenna structures within device 10
are being used to receive and process data. As an example,
circuitry 28 may control which of two or more antennas is being
used to receive incoming radio-frequency signals, may control which
of two or more antennas is being used to transmit radio-frequency
signals, may control the process of routing incoming data streams
over two or more antennas in device 10 in parallel, etc. In
performing these control operations, circuitry 28 may open and
close switches, may turn on and off receivers and transmitters, may
adjust impedance matching circuits, may configure switches in
front-end-module (FEM) radio-frequency circuits that are interposed
between radio-frequency transceiver circuitry and antenna
structures (e.g., filtering and switching circuits used for
impedance matching and signal routing), and may otherwise control
and adjust the components of device 10.
[0040] Input-output circuitry 30 may be used to allow data to be
supplied to device 10 and to allow data to be provided from device
10 to external devices. Input-output circuitry 30 may include
input-output devices 32. Input-output devices 32 may include touch
screens, buttons, joysticks, click wheels, scrolling wheels, touch
pads, key pads, keyboards, microphones, speakers, tone generators,
vibrators, cameras, sensors, light-emitting diodes and other status
indicators, data ports, etc. A user can control the operation of
device 10 by supplying commands through input-output devices 32 and
may receive status information and other output from device 10
using the output resources of input-output devices 32.
[0041] Wireless communications circuitry 34 may include
radio-frequency (RF) transceiver circuitry formed from one or more
integrated circuits, power amplifier circuitry, low-noise input
amplifiers, passive RF components, one or more antennas, and other
circuitry for handling RF wireless signals. Wireless signals can
also be sent using light (e.g., using infrared communications).
[0042] Wireless communications circuitry 34 may include satellite
navigation system receiver circuitry such as Global Positioning
System (GPS) receiver circuitry 35 (e.g., for receiving satellite
positioning signals at 1575 MHz). Transceiver circuitry 36 may
handle 2.4 GHz and 5 GHz bands for WiFi.RTM. (IEEE 802.11)
communications and may handle the 2.4 GHz Bluetooth.RTM.
communications band. Circuitry 34 may use cellular telephone
transceiver circuitry 38 for handling wireless communications in
cellular telephone bands such as bands at 700 MHz, 710 MHz, 750
MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz or other
cellular telephone bands of interest.
[0043] Wireless communications circuitry 34 can include circuitry
for other short-range and long-range wireless links if desired. For
example, wireless communications circuitry 34 may include global
positioning system (GPS) receiver equipment, wireless circuitry for
receiving radio and television signals, paging circuits, etc. In
WiFi.RTM. and Bluetooth.RTM. links and other short-range wireless
links, wireless signals are typically used to convey data over tens
or hundreds of feet. In cellular telephone links and other
long-range links, wireless signals are typically used to convey
data over thousands of feet or miles.
[0044] Wireless communications circuitry 34 may include antennas
40. Antennas 40 may be formed using any suitable antenna types. For
example, antennas 40 may include antennas with resonating elements
that are formed from loop antenna structure, patch antenna
structures, inverted-F antenna structures, closed and open slot
antenna structures, planar inverted-F antenna structures, helical
antenna structures, strip antennas, monopoles, dipoles, hybrids of
these designs, etc. Different types of antennas may be used for
different bands and combinations of bands. For example, one type of
antenna may be used in forming a local wireless link antenna and
another type of antenna may be used in forming a remote wireless
link.
[0045] A cross-sectional side view of device 10 of FIG. 1 taken
along line 24-24 in FIG. 1 and viewed in direction 26 is shown in
FIG. 3. As shown in FIG. 3, display 14 may be mounted to the front
surface of device 10. Housing 12 may include sidewalls formed from
member 16 and one or more rear walls formed from structures such as
planar rear housing structure 42. Structure 42 may be formed from a
dielectric such as glass, ceramic, or plastic, and/or metals or
other suitable materials (e.g., fiber composites). Snaps, clips,
screws, adhesive, and other structures may be used in assembling
the parts of housing 12 together.
[0046] Device 10 may contain printed circuit boards such as printed
circuit board 46. Printed circuit board 46 and the other printed
circuit boards in device 10 may be formed from rigid printed
circuit board material (e.g., fiberglass-filled epoxy) or flexible
sheets of material such as polymers. Flexible printed circuit
boards ("flex circuits") may, for example, be formed from flexible
sheets of polyimide.
[0047] Printed circuit board 46 may contain interconnects such as
interconnects 48. Interconnects 48 may be formed from conductive
traces (e.g., traces of gold-plated copper or other metals).
Connectors such as connector 50 may be connected to interconnect 48
using solder or conductive adhesive (as examples). Integrated
circuits, discrete components such as resistors, capacitors, and
inductors, and other electronic components may be mounted to
printed circuit board 46.
[0048] Antennas in device 10 such as illustrative antenna 40 of
FIG. 3 may have antenna feed terminals. For example, each antenna
in device 10 may have a positive antenna feed terminal such as
positive antenna feed terminal 58 and a ground antenna feed
terminal such as ground antenna feed terminal 54. As shown in the
illustrative arrangement of FIG. 3, a transmission line path such
as coaxial cable 52 may be coupled between the antenna feed formed
from terminals 58 and 54 and transceiver circuitry in components 44
via connector 50 and interconnects 48. Components 44 may include
one or more integrated circuits for implementing wireless circuitry
34 of FIG. 2 (e.g., receiver 35 and transceiver circuits 36 and
38).
[0049] Connectors such as connector 50 may be used in coupling
transmission lines in device 10 to printed circuit boards such as
board 46. Connector 50 may be, for example, a coaxial cable
connector that is connected to printed circuit board 46 using
solder (as an example). Cable 52 may be a coaxial cable or other
transmission line. Examples of transmission lines that may be used
in device 10 include coaxial cables, microstrip and stripline
transmission lines formed from a flex circuit or rigid printed
circuit board, transmission lines that are formed from multiple
transmission line structures such as these, etc.
[0050] When coupled to the feed of antenna 40, transmission line 52
may be used to transmit and receive radio-frequency signals using
antenna 40. As shown in FIG. 3, terminal 58 may be coupled to
coaxial cable center connector 56. Terminal 54 may be connected to
a ground conductor in cable 52 (e.g., a conductive outer braid
conductor). Other arrangements may be used for coupling
transceivers in device 10 to antenna 40 if desired. For example,
impedance matching circuits may be used in coupling transceiver
circuitry to antenna structures. The arrangement of FIG. 3 is
merely illustrative.
[0051] In the illustrative example of FIG. 3, device 10 includes
antenna 40. To enhance signal quality and to cover multiple bands
of interest, device 10 may contain multiple antennas. With one
suitable arrangement, which is sometimes described herein as an
example, a WiFi.RTM. antenna may be located in region 22, a first
(e.g., a primary) cellular telephone antenna may be located in
region 20, and a second (e.g., secondary) cellular telephone
antenna may be located in region 22. The second cellular telephone
antenna may, if desired, be configured to receive GPS signals.
Illustrative wireless circuitry 34 that includes an antenna
arrangement of this type is shown in FIG. 4.
[0052] As shown in FIG. 4, wireless circuitry 34 may have
input-output ports such as ports 100 and 130 for interfacing with
digital data circuits in storage and processing circuitry 28.
Wireless circuitry 34 may include one or more integrated circuits
for implementing transceiver circuits such as baseband processor
102 and cellular telephone transceiver circuitry 38. Port 100 may
receive digital data from storage and processing circuitry 28 for
transmission over antenna 40L. Incoming data that has been received
by antennas 40U and 40L, cellular transceiver circuitry 38, and
baseband processor 102 may be supplied to storage and processing
circuitry 28 via port 100. Port 130 may be used to handle digital
data associated with transmitted and received wireless local area
network signals such as WiFi.RTM. signals (as an example). Outgoing
digital data that is supplied to port 130 by storage and processing
circuitry 28 may be transmitted using wireless local area network
transceiver circuitry 36, paths such as path 128, and one or more
antennas such as antenna 40WF. During data reception operations,
signals received by antenna 40WF may be provided to transceiver 36
via path 128. Transceiver 36 may convert the incoming signals to
digital data. The digital data may be provided to storage and
processing circuitry 28 via port 130. If desired, local signals
such as Bluetooth.RTM. signals may also be transmitted and received
via antennas such as antenna 40WF.
[0053] Transceiver circuitry 38 may include one or more
transmitters and one or more receivers. In the example of FIG. 4,
transceiver circuitry 38 includes radio-frequency transmitter 104
and radio-frequency receivers 110. Transmitter 104 and receivers
110 (i.e., receiver RX1 and receiver RX2) may be used to handle
cellular telephone communications. Signals that are received by
transmitter 104 over path 118 may be supplied to power amplifier
106 by transmitter 104. Power amplifier 106 may strengthen these
outgoing signals for transmission over antenna 40L. Incoming
signals that are received by antenna 40L may be amplified by low
noise amplifier 112 and provided to receiver RX1. Receiver RX1 may
provide data received from antenna 40U to processor 102 via path
118. Incoming signals that are received by antenna 40U may be
amplified by low noise amplifier 124 and provided to receiver RX2
(or to RX1 using a switch). Receiver RX2 may provide data received
from antenna 40L to processor 102 via path 118. Circuits such as
transmitter 104 and receivers 110 may each have multiple ports
(e.g., for handling different respective communications bands) and
may be implemented using one or more individual integrated
circuits.
[0054] Antennas 40U and 40L may be coupled to transceiver circuitry
38 using circuitry such as impedance matching circuitry, filters,
and switches. This circuitry, which is sometimes referred to as
front-end module (FEM) circuitry, can be controlled by storage and
processing circuitry in device 10 (e.g., control signals from a
processor such as baseband processor 102). As shown in the example
of FIG. 4, the front-end circuitry in wireless circuitry 34 may
include impedance matching circuitry 108 such as tunable matching
circuitry M1 and tunable matching circuitry M2. Impedance matching
circuitry M1 and M2 may be formed using conductive structures with
associated capacitance, resistance, and inductance values, and/or
discrete components such as inductors, capacitors, and resistors
that form circuits to match the impedances of transceiver circuitry
38 and antennas 40U and 40L. Matching circuitry M1 may be coupled
between wireless transceiver circuitry 38 (including associated
amplifier circuitry 106 and 112) and antenna 40L. Matching
circuitry M2 may be coupled between transceiver circuitry 38 (and
associated amplifier 124) and antenna 40U using paths such as paths
132 and 122.
[0055] Matching circuitry M1 and M2 may be fixed or adjustable. For
example, matching circuitry M1 may be fixed and matching circuitry
M2 may be adjustable. As another example, matching circuitry M1 may
be adjustable and matching circuitry M2 may be fixed. As another
example, matching circuitry M1 and M2 may both be adjustable. In
this type of configuration, a control circuit such as baseband
processor 102 may issue control signals such as signal SELECT1 on
path 117 to configure tunable matching circuitry M1 and may issue
control signals such as signal SELECT2 on path 116 to configure
tunable matching circuitry M2.
[0056] Matching circuitry M1 may be placed in a first configuration
when SELECT1 has a first value and may be placed in a second
configuration when SELECT1 has a second value. The state of
matching circuitry M1 may serve to fine tune the coverage provided
by antenna 40L. Similarly, matching circuitry M2 may be placed in a
first configuration when SELECT2 has a first value and may be
placed in a second configuration when SELECT2 has a second value.
The state of matching circuitry M2 may serve to fine tune the
coverage provided by antenna 40U. Matching circuitry M1 and M2 may
or may not be used. By using an antenna tuning scheme of this type,
antennas 40L and 40U may be able to cover a wider range of
communications frequencies than would otherwise be possible. The
use of tuning for antennas 40L and 40U may allow a relatively
narrow bandwidth (and potentially compact) design to be used for
antennas 40L and 40U, if desired.
[0057] Control signals may be provided to receiver circuitry 110
over path 119 so that wireless circuitry 34 can selectively
activate one or both of receivers RX1 and RX2 or can otherwise
select which antenna signals are being received in real time (e.g.,
by controlling a multiplexer in circuitry 34 that routes signals
from a selected one of the antennas to a shared receiver so that
the receiver can be shared between antennas). For example, baseband
processor 102 or other storage and processing circuitry in device
10 can monitor signal quality (bit error rate, signal-to-noise
ratio, frame error rate, signal power, etc.) for signals being
received by antennas 40U and 40L. Based on real-time signal quality
information or other data (e.g., sensor data indicating that a
particular antenna is blocked), signals on path 119 or other
suitable control signals can be adjusted so that optimum receiver
circuitry (e.g., receiver RX1 or RX2) is used to receive the
incoming signals. Antenna diversity schemes such as this in which
circuitry 34 selects an optimum antenna and receiver to use in real
time based on signal quality measurements or other information
while radio-frequency signals are transmitted by a fixed antenna
and transmitter (i.e., antenna 40L and transmitter 104) may
sometimes be referred to as receiver diversity schemes.
[0058] In a receiver diversity configuration (i.e., in a device
without transmitter diversity), the radio-frequency transmitter
circuitry in a device is configured to receive signals through two
or more different antennas, so that an optimum antenna can be
chosen in real time to enhance signal reception, whereas the
radio-frequency transceiver circuitry is configured to transmit
signals through only a single one of the antennas and not others.
If desired, wireless circuitry 34 may be configured to implement
both receiver and transmitter diversity and/or may be configured to
handle multiple simultaneous data streams (e.g., using a MIMO
arrangement). The use of wireless circuitry 34 to implement a
receiver diversity scheme while using a dedicated antenna for
handling transmitted signals is merely illustrative.
[0059] As shown in FIG. 4, wireless circuitry 34 may be provided
with filter circuitry such as filter circuitry 126. Circuitry 126
may route signals by frequency, so that cellular telephone signals
are conveyed between antenna 40U and receiver RX2, whereas GPS
signals that are received by antenna 40U are routed to GPS receiver
35.
[0060] Illustrative configurable circuitry that may be used for
implementing matching circuitry M1 is shown in FIG. 5A. As shown in
FIG. 5A, matching circuitry M1 may have switches such as switches
134 and 136. Switches 134 and 136 may have multiple positions
(shown by the illustrative A and B positions in FIG. 5A). When
signal SELECT1 has a first value, switches 134 and 136 may be
placed in their A positions and matching circuit MA may be switched
into use (as shown in FIG. 5A), so that matching circuit MA is
electrically coupled between paths 120 and amplifiers 106 and 112.
When signal SELECT1 has a second value, switches 134 and 136 may be
placed in their B positions.
[0061] Illustrative configurable circuitry that may be used for
implementing matching circuitry M2 is shown in FIG. 5B. As shown in
FIG. 5B, matching circuitry M2 may have switches such as switches
134 and 136. Switches 134 and 136 may have multiple positions
(shown by the illustrative A and B positions in FIG. 5B). When
signal SELECT2 has a first value, switches 134 and 136 may be
placed in their A positions and matching circuit MA may be switched
into use. When signal SELECT2 has a second value, switches 134 and
136 may be placed in their B positions (as shown in FIG. 5B), so
that matching circuit MB is electrically coupled between paths 122
and 132.
[0062] FIG. 6 is a top view of the interior of device 10 showing
how antennas 40L, 40U, and 40WF may be implemented within housing
12. As shown in FIG. 6, ground plane G may be formed within housing
12. Ground plane G may form antenna ground for antennas 40L, 40U,
and 40WF. Because ground plane G may serve as antenna ground,
ground plane G may sometimes be referred to as antenna ground,
ground, or a ground plane element (as examples).
[0063] In central portion C of device 10, ground plane G may be
formed by conductive structures such as a conductive housing
midplate member that is connected between the left and right edges
of member 16, printed circuit boards with conductive ground traces,
etc. At ends 22 and 20 of device 10, the shape of ground plane G
may be determined by the shapes and locations of conductive
structures that are tied to ground. Examples of conductive
structures that may overlap to form ground plane G include housing
structures (e.g., a conductive housing midplate structure, which
may have protruding portions), conductive components (e.g.,
switches, cameras, data connectors, printed circuits such as flex
circuits and rigid printed circuit boards, radio-frequency
shielding cans, buttons such as button 144 and conductive button
mounting structure 146), and other conductive structures in device
10. In the illustrative layout of FIG. 6, the portions of device 10
that are conductive and tied to ground to form part of ground plane
G are shaded and are contiguous with central portion C.
[0064] Openings such as openings 72 and 140 may be formed between
ground plane G and respective portions of peripheral conductive
member 16. Openings 72 and 140 may be filled with air, plastic, and
other dielectrics. Opening 72 may be associated with antenna
structure 40L, whereas opening 140 may be associated with antenna
structures 40U and 40WF.
[0065] Gaps such as gaps 18B, 18C, and 18D may be present in
peripheral conductive member 16 (gap 18A of FIG. 1 may be absent or
may be implemented using a phantom gap structure that cosmetically
looks like a gap from the exterior of device 10, but that is
electrically shorted within the interior of housing 12 so that no
gap is electrically present in the location of gap 18A). The
presence of gaps 18B, 18C, and 18D may divide peripheral conductive
member 16 into segments. As shown in FIG. 6, peripheral conductive
member 16 may include first segment 16-1, second segment 16-2, and
third segment 16-3.
[0066] Lower antenna 40L may be formed using a parallel-fed loop
antenna structure having a shape that is determined at least partly
by the shape of the lower portions of ground plane G and conductive
housing segment 16-3. As shown in FIG. 6, antenna 40L may be formed
in lower region 20 of device 10. The portion of conductive segment
16-3 that surrounds opening 72 and the portions of ground plane G
that lie along edge GE of ground plane G form a conductive loop
around opening 72. The shape of opening 72 may be dictated by the
placement of conductive structures in region 20 such as a
microphone, flex circuit traces, a data port connector, buttons, a
speaker, etc.
[0067] Conductive structure 202 may bridge dielectric opening 72
and may be used to electrically short ground plane G to peripheral
housing segment 16-3. Conductive structure 202 may be formed using
strips of conductive material, flex circuit traces, conductive
housing structures, or other conductive structures. If desired,
conductive structure 202 may be formed using discrete components
such as surface mount technology (SMT) inductors. Transmission line
52-1 (e.g., a coaxial cable) may be used to feed antenna 40L at
positive and negative antenna feed terminals 58-1 and 54-1,
respectively.
[0068] Antenna 40L may include associated tunable (configurable)
antenna circuitry such as switchable inductor circuit 210, tunable
impedance matching circuitry Ml, variable capacitor circuit 212,
and other suitable tunable circuits. The tunable antenna circuitry
associated with antenna 40L may, for example, allow antenna 40L to
operate in at least six wireless communications bands (e.g., to
transmit and receive radio-frequency signals at 750 MHz, 800 MHz,
900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, etc.).
[0069] Conductive structure 202 may have a first conductive segment
SG and a second inductive segment SG' formed in series between
peripheral segment 16-3 and ground G. Segment SG may exhibit a
first inductance, segment SG' may exhibit a second inductance, and
circuit 202 may exhibit a third inductance. Switchable inductor
circuit (also referred to as tunable inductor circuit, configurable
inductor circuit, or adjustable inductor circuit) 210 may be
coupled between a point at which segments SG and SG' are joined and
a corresponding point 101 on ground plane edge GE.
[0070] When circuit 210 is switched into use (e.g., when circuit
210 is turned on), segment SG and circuit 210 collectively form a
first transmission line path that bridges the antenna feeds of
antenna 40L. The first transmission line path may have an
inductance that is equal to the series inductance of the first and
third inductance. When circuit 210 is switched out of use (e.g.,
when circuit 210 is turned off), segments SG and SG' may
collectively form a second transmission line path that bridges the
antenna feeds of antenna 40L. The second transmission line path may
have an inductance that is equal to the series inductance of the
first and second inductance. Switchable inductor 210 serves to
shunt a portion of the second transmission line path so that the
inductance associated with the first transmission line path when
circuit 210 is turned on is less than the inductance associated
with the second transmission line path when circuit 210 is turned
off.
[0071] The first transmission line inductance (i.e., the inductance
of the first transmission line path) may be different than the
second transmission line inductance (i.e., the inductance of the
second transmission line path). The first transmission line
inductance may be equal to 18 nH, whereas the second transmission
line inductance may be equal to 20 nH (as an example). The first
transmission line path (if circuit 210 is enabled) and the second
transmission line path (if circuit 210 is disabled) are connected
in parallel between feed terminals 54-1 and 58-1 and serve as
parallel inductive tuning elements for antenna 40L. The first and
second transmission line paths may therefore sometimes be referred
to as a variable inductor. The inductance of segments SG and SG'
are carefully chosen to provide desired band coverage.
[0072] Tunable impedance matching circuitry M1 may be coupled
between coaxial cable 52-1 and positive feed terminal 58-1.
Impedance matching circuitry M1 may be formed using switching
circuitry of the type described in connection with FIG. 5A,
conductive structures with associated capacitance, resistance, and
inductance values, and/or discrete components such as inductors,
capacitors, and resistors that form circuits to match the
impedances of transceiver circuitry 38 and antenna 40L.
[0073] Variable capacitor circuit (sometimes referred to as a
varactor circuit, a tunable capacitor circuit, an adjustable
capacitor circuit, etc.) 212 may be coupled between opposing ends
of bezel gap 18B. Baseband processor 102 may issue control voltage
VtuneB to fine tune varactor 212 so that antenna 40L operates at
desired frequencies.
[0074] Bezel gap 18B may, for example, have an intrinsic
capacitance of 1 pF (e.g., an inherent capacitance value formed by
the parallel conductive surfaces at gap 18B). Component 212 may be,
for example, a continuously variable capacitor, a semi-continuously
adjustable capacitor that has two to four or more different
capacitance values that can be coupled in parallel to the intrinsic
capacitance. If desired, component 212 may be a continuously
variable inductor or a semi-continuously adjustable inductor that
has two or more different inductance values.
[0075] Antenna 40WF may have an antenna resonating element formed
from a strip of conductor such as strip 142. Strip 142 may be
formed from a trace on a flex circuit, from a trace on a rigid
printed circuit board, from a strip of metal foil, or from other
conductive structures. Antenna 40WF may be fed by transmission line
52-2 (see, e.g., path 128 of FIG. 4) using antenna feed terminals
58-2 and 54-2.
[0076] Antenna 40U may include associated tunable (configurable)
antenna circuitry such as switchable inductor circuit 210', tunable
impedance matching circuitry M2, variable capacitor circuits 212-1
and 212-2, and other suitable tunable circuits. The tunable antenna
circuitry associated with antenna 40U may allow antenna 40U to have
a wider coverage than otherwise possible.
[0077] Antenna 40U may be a two-branch inverted-F antenna.
Transmission line 52-3 (see, e.g., path 120 of FIG. 4) may be used
to feed antenna 40U at antenna feed terminals 58-3 and 54-3.
Conductive structure 150 may be bridge dielectric opening 140 and
may be used to electrically short ground plane G to peripheral
housing member 16. Conductive structure 148 and matching circuitry
M2 may be used to connect antenna feed terminal 58-3 to peripheral
conductive member 16 at point 152. Conductive structures such as
structures 148 and 150 may be formed by flex circuit traces,
conductive housing structures, springs, screws, or other conductive
structures.
[0078] Peripheral conductive segment 16-1 may form antenna
resonating element arms for antenna 40U. In particular, a first
portion of segment 16-1 (having arm length LBA) may extend from
point 152 (where segment 16-1 is fed) to the end of segment 16-1
that is defined by gap 18C and a second portion of segment 16-1
(having arm length HBA) may extend from point 152 to the opposing
end of segment 16-1 that is defined by gap 18D. The first and
second portions of segment 16-1 may form respective branches of an
inverted F antenna and may be associated with respective low band
(LB) and high band (HB) antenna resonances for antenna 40U.
[0079] Switchable inductor circuit 210' may be coupled in parallel
with structures 148 and 150 between segment 16-1 and ground plane
G. Circuit 210' may be coupled to the right of structure 150 (as
shown in FIG. 6 when device 10 is viewed from the top) or may be
coupled to the left of structure 150. Circuit 210' may serve to
provide wider high band coverage for antenna 40U. Antenna 40U may
operate in a first high-band region when circuit 210' is switched
out of use, whereas antenna 40U may operate in a second high-band
region that is higher in frequency than the first high-band region
when circuit 210' is switched into use. For example, antenna 40U
may be used to receive signals in the 1900 MHz band when circuit
210' is turned off and in the 2100 MHz band when circuit 210' is
turned on.
[0080] Variable capacitor circuit 212-1 may be coupled between
opposing ends of conductive bezel gap 18C, whereas variable
capacitor circuit 212-2 may be coupled between opposing ends of
bezel gap 18D. Circuit 212-2 need not be formed, if desired.
Varactors 212-1 and 212-2 may be formed from using integrated
circuits, one or more discrete components (e.g., SMT components),
etc.
[0081] Variable capacitor 212-1 may serve to provide wider low-band
coverage for antenna 40U. Baseband processor 102 may issue control
voltage VtuneC to tune varactor 212-1 to configure antenna 40U to
operate in first and second low-band regions. For example, antenna
40U may be used to receive signals in the 850 MHz band when
varactor 212-1 is tuned to exhibit a low capacitance value (e.g.,
less than 0.1 pF) and to receive signals in the 750 MHz band when
varactor 212-1 is tuned to exhibit a high capacitance value (e.g.,
greater than 0.2 pF).
[0082] For example, bezel gaps 18C and 18D may each have an
intrinsic capacitance of 1.0 pF (e.g., an inherent capacitance
value formed by the parallel conductive surfaces at gaps 18C and
18D). Varactors 212-1 and 212-2 may be, for example, continuously
variable capacitors, semi-continuously adjustable capacitors that
have two to four or more different capacitance values that can be
coupled in parallel to the intrinsic capacitance.
[0083] FIG. 7 is a circuit diagram of antenna 40U. As shown in FIG.
7, capacitances C.sub.C and C.sub.D may respectively be associated
with gaps 18C and 18D. Capacitance C.sub.C may represent a lumped
capacitance that includes the parasitic capacitance of gap 18C and
varactor 212-1, whereas capacitance C.sub.D may represent a lumped
capacitance that includes the parasitic capacitance of gap 18D and
varactor 212-2. Ground plane G may form antenna ground. Short
circuit branch 150 may form a stub that connects peripheral
conductive member segment 16-1 to ground G to facilitate impedance
matching between the antenna feed (formed from feed terminals 58-3
and 54-3) and antenna 40U. Short circuit branch 150 may have an
associated inductance Ls.
[0084] Antenna 40U may be operable in a first high-band mode (e.g.,
a mode that covers band 1900 MHz) when circuit 210' is switched out
of use and a second high-band mode (e.g., a mode that covers band
2100 MHz) when circuit 210' is switched into use. FIG. 7 shows one
suitable circuit implementation of switchable inductor circuit
210'. As shown in FIG. 7, circuit 210 includes a switch SW and
inductive element 214 coupled in series. Switch SW may be
implemented using a p-i-n diode, a gallium arsenide field-effect
transistor (FET), a microelectromechanical systems (MEMs) switch, a
metal-oxide-semiconductor field-effect transistor (MOSFET), a
high-electron mobility transistor (HEMI), a pseudomorphic HEMI
(PHEMT), a transistor formed on a silicon-on-insulator (SOI)
substrate, etc.
[0085] Inductive element 214 may be formed from one or more
electrical components. Components that may be used as all or part
of element 214 include inductors and capacitors. Desired
inductances and capacitances for element 214 may be formed using
integrated circuits, using discrete components (e.g., a surface
mount technology inductor) and/or using dielectric and conductive
structures that are not part of a discrete component or an
integrated circuit. For example, capacitance can be formed by
spacing two conductive pads close to each other that are separated
by a dielectric, and an inductance can be formed by creating a
conductive path (e.g., a transmission line) on a printed circuit
board.
[0086] In another suitable arrangement, configurable inductor
circuit 209 may be used to form a shorting path for antenna 40U
(i.e., shorting structure 150 and circuit 210' of FIG. 7 are not
formed). As shown in FIG. 8, circuit 209 may include inductors 214
and 216 coupled between conductive segment 16-1 and switch 218.
Switch 218 may have multiple positions (shown by the illustrative A
and B positions). Switch 218 may be placed in it's A position to
couple inductor 214 between the antenna feeds (e.g., between
positive and negative terminals 58-3 and 54-3) during the second
high-band mode and may be placed in its B position to coupled
inductor 216 between the antenna feeds during the first high-band
mode. Inductor 216 may have an inductance value that is
approximately equal to Ls (FIG. 8), as an example.
[0087] In another suitable arrangement, configurable inductor
circuit 211 may be used to form a shorting path for antenna 40U
(i.e., shorting structure 150 and circuit 210' of FIG. 7 are not
formed). As shown in FIG. 9, circuit 211 may include inductor 214
and first switch SW coupled in series between segment 16-1 and
ground G and may include inductor 216 and second switch SW coupled
in series between segment 16-1 and ground G. During the first
high-band mode, first switch SW may be open and second switch SW
may be closed to electrically connect inductor 216 between the
antenna feed terminals. During the second high-band mode, second
switch SW may be disabled and first switch may be enabled to
electrically connect inductor 214 between the antenna feed
terminals.
[0088] FIGS. 7-9 are merely illustrative. If desired, antenna 40U
may include more than two inductive branches to support wireless
coverage in more than two low-band regions.
[0089] Antenna 40L may cover at least six transmit and receive
communications bands (e.g., 700 MHz, 850 MHz, 900 MHz, 1800 MHz,
1900 MHz, and 2100 MHz), as shown in the table of FIG. 10. Antenna
40U may be configured to cover a subset of these six illustrative
communications bands. For example, antenna 40U may be configured to
cover three receive bands of interest and, with tuning, six receive
bands of interest.
[0090] Antenna 40U may be configured in a first operating mode in
which capacitor 212-1 is tuned to provide a first capacitance value
and in which inductor circuit 210' is turned off. In the first
operating mode (see, e.g., row 250 in FIG. 10), antenna 40U may be
capable of covering receive bands 850 RX (the 850 MHz receive
band), 900 RX (the 900 MHz receive band), 1800 RX (the 1800 MHz
receive band), 1900 RX (the 1900 MHz receive band), and any other
communications bands of interest.
[0091] Antenna 40U may be configured in a second operating mode in
which capacitor 212-1 is tuned to provide a second capacitance
value that is higher than the first capacitance value and in which
inductor circuit 210' is off. In the second operating mode (see,
e.g., row 252 in FIG. 10), antenna 40U may be capable of covering
receive bands 750 RX (the 750 MHz receive band), 1800 RX, 1900 RX,
and other communications bands of interest.
[0092] Antenna 40U may be configured in a third operating mode in
which capacitor 212-1 is tuned to provide the first capacitance
value and in which inductor circuit 210' is turned on. In the third
operating mode (see, e.g., row 254 in FIG. 10), antenna 40U may be
capable of covering receive bands 850 RX, 900 RX, 2100 RX (the 2100
MHz receive band), and other communications bands of interest.
[0093] The modes described in connection with FIG. 10 are merely
illustrative. If desired, circuit 210' may be turned on/off and
capacitor 212-1 may be tuned to provide suitable capacitance to
cover desired high-band and low-band frequency ranges of interest.
If desired, antenna 40U may also be used to transmit
radio-frequency signals in the indicated bands.
[0094] By using antenna tuning schemes of the type described in
connection with FIGS. 4-10, antenna 40L and 40U may be able to
cover a wider range of communications frequencies than would
otherwise be possible. A standing-wave-ratio (SWR) versus frequency
plot such as SWR plot of FIG. 11 illustrates low-band tuning
capability for antenna 40U. As shown in FIG. 11, solid SWR
frequency characteristic curve 300 corresponds to a first antenna
tuning mode in which antenna 40U of device 10 exhibits satisfactory
resonant peaks at low-band frequency f1 (to cover the 850 MHz band)
and high-band frequency f2 (e.g., to cover the 1900 MHz band). In
the first antenna tuning mode, variable capacitor circuit 212-1 may
be tuned to a first capacitance, whereas switchable inductor
circuit 210' is turned off.
[0095] Dotted SWR frequency characteristic curve 302 corresponds to
a second antenna tuning mode in which the antennas of device 10
exhibits satisfactory resonant peaks at low-band frequency f1' (to
cover the 750 MHz band) and high-band frequency f2. In the second
antenna tuning mode, variable capacitor circuit 212-1 may be tuned
to a second capacitance that is greater than the first capacitance
to shift the wireless coverage from frequency f1 to f1'.
[0096] FIG. 12 illustrates antenna 40U operating in a third antenna
tuning mode. As shown in FIG. 12, dotted SWR frequency
characteristic curve 304 corresponds to the third antenna tuning
mode in which antenna 40U exhibits satisfactory resonant peaks at
low-band frequency fl and high-band frequency f2' (to cover the
2100 MHz band). In the third antenna tuning mode, circuit 210' is
switched into use to shift the wireless coverage from frequency f2
to f2'.
[0097] In general, the switchable inductor circuits described in
connection with FIGS. 7-9 can be used to tune the high-band
coverage for antenna 40U (e.g., the switchable inductor circuits
may be configured in at least two states to provide wireless
coverage in at least two high-band frequency ranges), whereas
variable capacitor 212-2 may be tuned to adjust the low-band
coverage for antenna 40U (e.g., the variable capacitor associated
with low-band gap 18C may be tuned to provide wireless coverage in
at least two low-band frequency ranges). FIGS. 11 and 12 are merely
illustrative. If desired, antennas 40L, 40U, and 40WF may include
antenna tuning circuitry that enables device 10 to transmit and
receive wireless signals at any suitable number of radio-frequency
communications bands.
[0098] The foregoing is merely illustrative of the principles of
this invention and various modifications can be made by those
skilled in the art without departing from the scope and spirit of
the invention.
* * * * *